bond certificate vs obligation

bond certificate and obligation both are nouns.

Word	Noun	Adjective	Verb	Adverb
bond certificate	Yes	No	No	No
obligation	Yes	No	No	No

As nouns, obligation is a hypernym of bond certificate; that is, obligation is a word with a broader meaning than bond certificate:

bond certificate: a certificate of debt (usually interest-bearing or discounted) that is issued by a government or corporation in order to raise money; the issuer is required to pay a fixed sum annually until maturity and then a fixed sum to repay the principal
obligation: a written promise to repay a debt

Other hypernyms of bond certificate include certificate of indebtedness, debt instrument, certificate, security.

bond certificate (noun)	obligation (noun)
a certificate of debt (usually interest-bearing or discounted) that is issued by a government or corporation in order to raise money; the issuer is required to pay a fixed sum annually until maturity and then a fixed sum to repay the principal	the social force that binds you to the courses of action demanded by that force
	a legal agreement specifying a payment or action and the penalty for failure to comply
	a written promise to repay a debt
	a personal relation in which one is indebted for a service or favor
	the state of being obligated to do or pay something